angular - 如何获取 Angular Material slider 的当前值？

Question

My question is different to Get mdslider value in angular 2? in that I needed to pass the value of the slider to the component, not just use a local variable; but also in respect of Angular Material having changed so that the slider now requires an $event object to be passed to the component function.

我在 Angular 4 中有一个 Angular Material slider 组件:

HTML

<mat-slider min="430" max="500" step="10" value="450" (input)="pitch($event)"></mat-slider>

TS

import { Component, OnInit } from '@angular/core';
import { Inject, Injectable } from '@angular/core';
import { MatSlider } from '@angular/material';
import { AudioContext } from 'angular-audio-context';

@Component({
  selector: 'pitch-slider',
  templateUrl: './pitch-slider.component.html',
  styleUrls: ['./pitch-slider.component.css']
})


export class PitchSliderComponent implements OnInit {



  constructor(private _audioContext: AudioContext) { }

  ngOnInit() {
  }

}

我对 Angular 很陌生，无法获取 slider 的当前值。它似乎不适用于 $event 对象？

Answer 1

我对 $event 对象感到困惑 - 我需要仅使用 component.ts 中的事件来引用它:

HTML

<h2>freq.</h2>
  <button class="btn btn-primary" (click)="play()">Play</button>
  <mat-slider min="430" max="500" step="10" #matslider (input)="pitch($event)"></mat-slider>

      <div>
        {{ matslider.value }}
      </div>

TS

import { Component, OnInit } from '@angular/core';
import { Inject, Injectable } from '@angular/core';
import { MatSlider } from '@angular/material';
import { AudioContext } from 'angular-audio-context';


@Component({
  selector: 'pitch-slider',
  templateUrl: './pitch-slider.component.html',
  styleUrls: ['./pitch-slider.component.css']
})


export class PitchSliderComponent implements OnInit {
  value: 450;

  constructor(private _audioContext: AudioContext) { }

  ngOnInit() {
  }

  pitch(event: any) {
  console.log(event.value);
}

  play() {
    console.log("play clicked!");
    var frequency = this.value;
    var volume = 0.2;
    var oscillator = this._audioContext.createOscillator();
    var gainNode = this._audioContext.createGain();

    oscillator.connect(gainNode);
    gainNode.connect(this._audioContext.destination);

    gainNode.gain.value = volume;
    oscillator.frequency.value = frequency;

    oscillator.start();

    setTimeout(
      function(){
        oscillator.stop();
      }, 500
    );
  }

}